Shutter Mount Exhaust Fan, Assembled Assembled, Blade Diameter 18 in, Blade Material Aluminum, Control Type Pull Chain, Drive Type Direct Drive, Duct Diameter 18 3/8 in, Exhaust Airflow @ 0.000 in SP 1,877 cfm, For -Out Height 19 in, For -Out Width 19 in, For Maximum Wall Thickness 5 1/2 in, For Minimum Wall Thickness 3 in, Frame Material Aluminum, Guard Finish Chrome, Guard Material Steel, Guard Type Exhaust, Housing Material Aluminum; Steel, Housing Finish Galvanized